1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- A C C E S S I B I L I T Y --
9 -- Copyright (C) 2022-2024, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree
; use Atree
;
27 with Checks
; use Checks
;
28 with Debug
; use Debug
;
29 with Einfo
; use Einfo
;
30 with Einfo
.Entities
; use Einfo
.Entities
;
31 with Elists
; use Elists
;
32 with Errout
; use Errout
;
33 with Einfo
.Utils
; use Einfo
.Utils
;
34 with Exp_Atag
; use Exp_Atag
;
35 with Exp_Ch7
; use Exp_Ch7
;
36 with Exp_Tss
; use Exp_Tss
;
37 with Exp_Util
; use Exp_Util
;
38 with Namet
; use Namet
;
39 with Nlists
; use Nlists
;
40 with Nmake
; use Nmake
;
42 with Restrict
; use Restrict
;
43 with Rtsfind
; use Rtsfind
;
45 with Sem_Aux
; use Sem_Aux
;
46 with Sem_Ch8
; use Sem_Ch8
;
47 with Sem_Res
; use Sem_Res
;
48 with Sem_Util
; use Sem_Util
;
49 with Sinfo
; use Sinfo
;
50 with Sinfo
.Nodes
; use Sinfo
.Nodes
;
51 with Sinfo
.Utils
; use Sinfo
.Utils
;
52 with Snames
; use Snames
;
53 with Stand
; use Stand
;
54 with Tbuild
; use Tbuild
;
56 package body Accessibility
is
58 ---------------------------
59 -- Accessibility_Message --
60 ---------------------------
62 procedure Accessibility_Message
(N
: Node_Id
; Typ
: Entity_Id
) is
63 Loc
: constant Source_Ptr
:= Sloc
(N
);
64 P
: constant Node_Id
:= Prefix
(N
);
65 Indic
: Node_Id
:= Parent
(Parent
(N
));
68 -- In an instance, this is a runtime check, but one we know will fail,
69 -- so generate an appropriate warning.
71 if In_Instance_Body
then
72 Error_Msg_Warn
:= SPARK_Mode
/= On
;
74 ("non-local pointer cannot point to local object<<", P
);
75 Error_Msg_F
("\Program_Error [<<", P
);
77 Make_Raise_Program_Error
(Loc
,
78 Reason
=> PE_Accessibility_Check_Failed
));
83 Error_Msg_F
("non-local pointer cannot point to local object", P
);
85 -- Check for case where we have a missing access definition
87 if Is_Record_Type
(Current_Scope
)
89 Nkind
(Parent
(N
)) in N_Discriminant_Association
90 | N_Index_Or_Discriminant_Constraint
92 Indic
:= Parent
(Parent
(N
));
94 and then Nkind
(Indic
) /= N_Subtype_Indication
96 Indic
:= Parent
(Indic
);
99 if Present
(Indic
) then
101 ("\use an access definition for" &
102 " the access discriminant of&",
103 N
, Entity
(Subtype_Mark
(Indic
)));
107 end Accessibility_Message
;
109 -------------------------
110 -- Accessibility_Level --
111 -------------------------
113 function Accessibility_Level
115 Level
: Accessibility_Level_Kind
;
116 In_Return_Context
: Boolean := False;
117 Allow_Alt_Model
: Boolean := True) return Node_Id
119 Loc
: constant Source_Ptr
:= Sloc
(Expr
);
121 function Accessibility_Level
(Expr
: Node_Id
) return Node_Id
is
123 (Expr
, Level
, In_Return_Context
, Allow_Alt_Model
));
124 -- Renaming of the enclosing function to facilitate recursive calls
126 function Make_Level_Literal
(Level
: Uint
) return Node_Id
;
127 -- Construct an integer literal representing an accessibility level with
128 -- its type set to Natural.
130 function Innermost_Master_Scope_Depth
(N
: Node_Id
) return Uint
;
131 -- Returns the scope depth of the given node's innermost enclosing scope
132 -- (effectively the accessibility level of the innermost enclosing
135 function Function_Call_Or_Allocator_Level
(N
: Node_Id
) return Node_Id
;
136 -- Centralized processing of subprogram calls which may appear in prefix
139 function Typ_Access_Level
(Typ
: Entity_Id
) return Uint
140 is (Type_Access_Level
(Typ
, Allow_Alt_Model
));
141 -- Renaming of Type_Access_Level with Allow_Alt_Model specified to avoid
142 -- passing the parameter specifically in every call.
144 ----------------------------------
145 -- Innermost_Master_Scope_Depth --
146 ----------------------------------
148 function Innermost_Master_Scope_Depth
(N
: Node_Id
) return Uint
is
149 Encl_Scop
: Entity_Id
;
151 Node_Par
: Node_Id
:= Parent
(N
);
152 Master_Lvl_Modifier
: Int
:= 0;
155 -- Locate the nearest enclosing node (by traversing Parents)
156 -- that Defining_Entity can be applied to, and return the
157 -- depth of that entity's nearest enclosing scope.
159 -- The RM 7.6.1(3) definition of "master" includes statements
160 -- and conditions for loops among other things. Are these cases
161 -- detected properly ???
163 while Present
(Node_Par
) loop
164 Ent
:= Defining_Entity_Or_Empty
(Node_Par
);
166 if Present
(Ent
) then
167 -- X'Old is nested within the current subprogram, so we do not
168 -- want Find_Enclosing_Scope of that subprogram. If this is an
169 -- allocator, then we're looking for the innermost master of
170 -- the call, so again we do not want Find_Enclosing_Scope.
172 if (Nkind
(N
) = N_Attribute_Reference
173 and then Attribute_Name
(N
) = Name_Old
)
174 or else Nkind
(N
) = N_Allocator
178 Encl_Scop
:= Find_Enclosing_Scope
(Ent
);
181 -- Ignore transient scopes made during expansion while also
182 -- taking into account certain expansions - like iterators
183 -- which get expanded into renamings and thus not marked
184 -- as coming from source.
186 if Comes_From_Source
(Node_Par
)
187 or else (Nkind
(Node_Par
) = N_Object_Renaming_Declaration
188 and then Comes_From_Iterator
(Node_Par
))
190 -- Note that in some rare cases the scope depth may not be
191 -- set, for example, when we are in the middle of analyzing
192 -- a type and the enclosing scope is said type. In that case
193 -- simply return zero for the outermost scope.
195 if Scope_Depth_Set
(Encl_Scop
) then
196 return Scope_Depth
(Encl_Scop
) + Master_Lvl_Modifier
;
202 -- For a return statement within a function, return
203 -- the depth of the function itself. This is not just
204 -- a small optimization, but matters when analyzing
205 -- the expression in an expression function before
206 -- the body is created.
208 elsif Nkind
(Node_Par
) in N_Extended_Return_Statement
209 | N_Simple_Return_Statement
211 return Scope_Depth
(Enclosing_Subprogram
(Node_Par
));
213 -- Statements are counted as masters
215 elsif Is_Master
(Node_Par
) then
216 Master_Lvl_Modifier
:= Master_Lvl_Modifier
+ 1;
220 Node_Par
:= Parent
(Node_Par
);
223 -- Should never reach the following return
225 pragma Assert
(False);
227 return Scope_Depth
(Current_Scope
) + 1;
228 end Innermost_Master_Scope_Depth
;
230 ------------------------
231 -- Make_Level_Literal --
232 ------------------------
234 function Make_Level_Literal
(Level
: Uint
) return Node_Id
is
235 Result
: constant Node_Id
:= Make_Integer_Literal
(Loc
, Level
);
238 Set_Etype
(Result
, Standard_Natural
);
240 end Make_Level_Literal
;
242 --------------------------------------
243 -- Function_Call_Or_Allocator_Level --
244 --------------------------------------
246 function Function_Call_Or_Allocator_Level
(N
: Node_Id
) return Node_Id
is
250 -- Results of functions are objects, so we either get the
251 -- accessibility of the function or, in case of a call which is
252 -- indirect, the level of the access-to-subprogram type.
254 -- This code looks wrong ???
256 if Nkind
(N
) = N_Function_Call
257 and then Ada_Version
< Ada_2005
259 if Is_Entity_Name
(Name
(N
)) then
260 return Make_Level_Literal
261 (Subprogram_Access_Level
(Entity
(Name
(N
))));
263 return Make_Level_Literal
264 (Typ_Access_Level
(Etype
(Prefix
(Name
(N
)))));
267 -- We ignore coextensions as they cannot be implemented under the
268 -- "small-integer" model.
270 elsif Nkind
(N
) = N_Allocator
271 and then (Is_Static_Coextension
(N
)
272 or else Is_Dynamic_Coextension
(N
))
274 return Make_Level_Literal
(Scope_Depth
(Standard_Standard
));
277 -- Named access types have a designated level
279 if Is_Named_Access_Type
(Etype
(N
)) then
280 return Make_Level_Literal
(Typ_Access_Level
(Etype
(N
)));
282 -- Otherwise, the level is dictated by RM 3.10.2 (10.7/3)
285 -- Check No_Dynamic_Accessibility_Checks restriction override for
286 -- alternative accessibility model.
289 and then No_Dynamic_Accessibility_Checks_Enabled
(N
)
290 and then Is_Anonymous_Access_Type
(Etype
(N
))
292 -- In the alternative model the level is that of the
295 if Debug_Flag_Underscore_B
then
296 return Make_Level_Literal
(Typ_Access_Level
(Etype
(N
)));
298 -- For function calls the level is that of the innermost
299 -- master, otherwise (for allocators etc.) we get the level
300 -- of the corresponding anonymous access type, which is
301 -- calculated through the normal path of execution.
303 elsif Nkind
(N
) = N_Function_Call
then
304 return Make_Level_Literal
305 (Innermost_Master_Scope_Depth
(Expr
));
309 if Nkind
(N
) = N_Function_Call
then
310 -- Dynamic checks are generated when we are within a return
311 -- value or we are in a function call within an anonymous
312 -- access discriminant constraint of a return object (signified
313 -- by In_Return_Context) on the side of the callee.
315 -- So, in this case, return accessibility level of the
316 -- enclosing subprogram.
318 if In_Return_Value
(N
)
319 or else In_Return_Context
321 return Make_Level_Literal
322 (Subprogram_Access_Level
(Current_Subprogram
));
326 -- When the call is being dereferenced the level is that of the
327 -- enclosing master of the dereferenced call.
329 if Nkind
(Parent
(N
)) in N_Explicit_Dereference
330 | N_Indexed_Component
331 | N_Selected_Component
333 return Make_Level_Literal
334 (Innermost_Master_Scope_Depth
(Expr
));
337 -- Find any relevant enclosing parent nodes that designate an
338 -- object being initialized.
340 -- Note: The above is only relevant if the result is used "in its
341 -- entirety" as RM 3.10.2 (10.2/3) states. However, this is
342 -- accounted for in the case statement in the main body of
343 -- Accessibility_Level for N_Selected_Component.
345 Par
:= Parent
(Expr
);
347 while Present
(Par
) loop
348 -- Detect an expanded implicit conversion, typically this
349 -- occurs on implicitly converted actuals in calls.
351 -- Does this catch all implicit conversions ???
353 if Nkind
(Par
) = N_Type_Conversion
354 and then Is_Named_Access_Type
(Etype
(Par
))
356 return Make_Level_Literal
357 (Typ_Access_Level
(Etype
(Par
)));
360 -- Jump out when we hit an object declaration or the right-hand
361 -- side of an assignment, or a construct such as an aggregate
362 -- subtype indication which would be the result is not used
363 -- "in its entirety."
365 exit when Nkind
(Par
) in N_Object_Declaration
366 or else (Nkind
(Par
) = N_Assignment_Statement
367 and then Name
(Par
) /= Prev_Par
);
373 -- Assignment statements are handled in a similar way in
374 -- accordance to the left-hand part. However, strictly speaking,
375 -- this is illegal according to the RM, but this change is needed
376 -- to pass an ACATS C-test and is useful in general ???
379 when N_Object_Declaration
=>
380 return Make_Level_Literal
382 (Scope
(Defining_Identifier
(Par
))));
384 when N_Assignment_Statement
=>
385 -- Return the accessibility level of the left-hand part
387 return Accessibility_Level
389 Level
=> Object_Decl_Level
,
390 In_Return_Context
=> In_Return_Context
);
393 return Make_Level_Literal
394 (Innermost_Master_Scope_Depth
(Expr
));
397 end Function_Call_Or_Allocator_Level
;
404 -- Start of processing for Accessibility_Level
407 -- We could be looking at a reference to a formal due to the expansion
408 -- of entries and other cases, so obtain the renaming if necessary.
410 if Present
(Param_Entity
(Expr
)) then
411 E
:= Param_Entity
(Expr
);
413 -- Use the original node unless it is an unanalyzed identifier, as we
414 -- don't want to reason on unanalyzed expressions from predicates.
416 elsif Nkind
(Original_Node
(Expr
)) /= N_Identifier
417 or else Analyzed
(Original_Node
(Expr
))
419 E
:= Original_Node
(Expr
);
425 -- Extract the entity
427 if Nkind
(E
) in N_Has_Entity
and then Present
(Entity
(E
)) then
430 -- Deal with a possible renaming of a private protected component
432 if Ekind
(E
) in E_Constant | E_Variable
and then Is_Prival
(E
) then
433 E
:= Prival_Link
(E
);
437 -- Perform the processing on the expression
440 -- The level of an aggregate is that of the innermost master that
441 -- evaluates it as defined in RM 3.10.2 (10/4).
444 return Make_Level_Literal
(Innermost_Master_Scope_Depth
(Expr
));
446 -- The accessibility level is that of the access type, except for
447 -- anonymous allocators which have special rules defined in RM 3.10.2
451 return Function_Call_Or_Allocator_Level
(E
);
453 -- We could reach this point for two reasons. Either the expression
454 -- applies to a special attribute ('Loop_Entry, 'Result, or 'Old), or
455 -- we are looking at the access attributes directly ('Access,
456 -- 'Address, or 'Unchecked_Access).
458 when N_Attribute_Reference
=>
459 Pre
:= Original_Node
(Prefix
(E
));
461 -- Regular 'Access attribute presence means we have to look at the
464 if Attribute_Name
(E
) = Name_Access
then
465 return Accessibility_Level
(Prefix
(E
));
467 -- Unchecked or unrestricted attributes have unlimited depth
469 elsif Attribute_Name
(E
) in Name_Address
470 | Name_Unchecked_Access
471 | Name_Unrestricted_Access
473 return Make_Level_Literal
(Scope_Depth
(Standard_Standard
));
475 -- 'Access can be taken further against other special attributes,
476 -- so handle these cases explicitly.
478 elsif Attribute_Name
(E
)
489 -- Named access types
491 if Is_Named_Access_Type
(Etype
(Pre
)) then
492 return Make_Level_Literal
493 (Typ_Access_Level
(Etype
(Pre
)));
495 -- Anonymous access types
497 elsif Nkind
(Pre
) in N_Has_Entity
498 and then Ekind
(Entity
(Pre
)) not in Subprogram_Kind
499 and then Present
(Get_Dynamic_Accessibility
(Entity
(Pre
)))
500 and then Level
= Dynamic_Level
502 pragma Assert
(Is_Anonymous_Access_Type
(Etype
(Pre
)));
503 return New_Occurrence_Of
504 (Get_Dynamic_Accessibility
(Entity
(Pre
)), Loc
);
506 -- Otherwise the level is treated in a similar way as
507 -- aggregates according to RM 6.1.1 (35.1/4) which concerns
508 -- an implicit constant declaration - in turn defining the
509 -- accessibility level to be that of the implicit constant
513 return Make_Level_Literal
514 (Innermost_Master_Scope_Depth
(Expr
));
521 -- This is the "base case" for accessibility level calculations which
522 -- means we are near the end of our recursive traversal.
524 when N_Defining_Identifier
=>
525 -- A dynamic check is performed on the side of the callee when we
526 -- are within a return statement, so return a library-level
527 -- accessibility level to null out checks on the side of the
530 if Is_Explicitly_Aliased
(E
)
531 and then (In_Return_Context
532 or else (Level
/= Dynamic_Level
533 and then In_Return_Value
(Expr
)))
535 return Make_Level_Literal
(Scope_Depth
(Standard_Standard
));
537 -- Something went wrong and an extra accessibility formal has not
538 -- been generated when one should have ???
541 and then No
(Get_Dynamic_Accessibility
(E
))
542 and then Ekind
(Etype
(E
)) = E_Anonymous_Access_Type
544 return Make_Level_Literal
(Scope_Depth
(Standard_Standard
));
546 -- Stand-alone object of an anonymous access type "SAOAAT"
549 or else Ekind
(E
) in E_Variable
551 and then Present
(Get_Dynamic_Accessibility
(E
))
552 and then (Level
= Dynamic_Level
553 or else Level
= Zero_On_Dynamic_Level
)
555 if Level
= Zero_On_Dynamic_Level
then
556 return Make_Level_Literal
557 (Scope_Depth
(Standard_Standard
));
560 -- No_Dynamic_Accessibility_Checks restriction override for
561 -- alternative accessibility model.
564 and then No_Dynamic_Accessibility_Checks_Enabled
(E
)
566 -- In the alternative model the level is that of the
567 -- designated type entity's context.
569 if Debug_Flag_Underscore_B
then
570 return Make_Level_Literal
(Typ_Access_Level
(Etype
(E
)));
572 -- Otherwise the level depends on the entity's context
574 elsif Is_Formal
(E
) then
575 return Make_Level_Literal
576 (Subprogram_Access_Level
577 (Enclosing_Subprogram
(E
)));
579 return Make_Level_Literal
580 (Scope_Depth
(Enclosing_Dynamic_Scope
(E
)));
584 -- Return the dynamic level in the normal case
586 return New_Occurrence_Of
587 (Get_Dynamic_Accessibility
(E
), Loc
);
589 -- Initialization procedures have a special extra accessibility
590 -- parameter associated with the level at which the object
591 -- being initialized exists
593 elsif Ekind
(E
) = E_Record_Type
594 and then Is_Limited_Record
(E
)
595 and then Current_Scope
= Init_Proc
(E
)
596 and then Present
(Init_Proc_Level_Formal
(Current_Scope
))
598 return New_Occurrence_Of
599 (Init_Proc_Level_Formal
(Current_Scope
), Loc
);
601 -- Current instance of the type is deeper than that of the type
602 -- according to RM 3.10.2 (21).
604 elsif Is_Type
(E
) then
605 -- When restriction No_Dynamic_Accessibility_Checks is active
606 -- along with -gnatd_b.
609 and then No_Dynamic_Accessibility_Checks_Enabled
(E
)
610 and then Debug_Flag_Underscore_B
612 return Make_Level_Literal
(Typ_Access_Level
(E
));
617 return Make_Level_Literal
(Typ_Access_Level
(E
) + 1);
619 -- Move up the renamed entity or object if it came from source
620 -- since expansion may have created a dummy renaming under
621 -- certain circumstances.
623 -- Note: We check if the original node of the renaming comes
624 -- from source because the node may have been rewritten.
626 elsif Present
(Renamed_Entity_Or_Object
(E
))
627 and then Comes_From_Source
628 (Original_Node
(Renamed_Entity_Or_Object
(E
)))
630 return Accessibility_Level
(Renamed_Entity_Or_Object
(E
));
632 -- Named access types get their level from their associated type
634 elsif Is_Named_Access_Type
(Etype
(E
)) then
635 return Make_Level_Literal
636 (Typ_Access_Level
(Etype
(E
)));
638 -- Check if E is an expansion-generated renaming of an iterator
639 -- by examining Related_Expression. If so, determine the
640 -- accessibility level based on the original expression.
642 elsif Ekind
(E
) in E_Constant | E_Variable
643 and then Present
(Related_Expression
(E
))
645 return Accessibility_Level
(Related_Expression
(E
));
647 elsif Level
= Dynamic_Level
648 and then Ekind
(E
) in E_In_Parameter | E_In_Out_Parameter
649 and then Present
(Init_Proc_Level_Formal
(Scope
(E
)))
651 return New_Occurrence_Of
652 (Init_Proc_Level_Formal
(Scope
(E
)), Loc
);
654 -- Normal object - get the level of the enclosing scope
657 return Make_Level_Literal
658 (Scope_Depth
(Enclosing_Dynamic_Scope
(E
)));
661 -- Handle indexed and selected components including the special cases
662 -- whereby there is an implicit dereference, a component of a
663 -- composite type, or a function call in prefix notation.
665 -- We don't handle function calls in prefix notation correctly ???
667 when N_Indexed_Component | N_Selected_Component | N_Slice
=>
670 -- Fetch the original node when the prefix comes from the result
671 -- of expanding a function call since we want to find the level
672 -- of the original source call.
674 if not Comes_From_Source
(Pre
)
675 and then Nkind
(Original_Node
(Pre
)) = N_Function_Call
677 Pre
:= Original_Node
(Pre
);
680 -- When E is an indexed component or selected component and
681 -- the current Expr is a function call, we know that we are
682 -- looking at an expanded call in prefix notation.
684 if Nkind
(Expr
) = N_Function_Call
then
685 return Function_Call_Or_Allocator_Level
(Expr
);
687 -- If the prefix is a named access type, then we are dealing
688 -- with an implicit deferences. In that case the level is that
689 -- of the named access type in the prefix.
691 elsif Is_Named_Access_Type
(Etype
(Pre
)) then
692 return Make_Level_Literal
693 (Typ_Access_Level
(Etype
(Pre
)));
695 -- The current expression is a named access type, so there is no
696 -- reason to look at the prefix. Instead obtain the level of E's
697 -- named access type.
699 elsif Is_Named_Access_Type
(Etype
(E
)) then
700 return Make_Level_Literal
701 (Typ_Access_Level
(Etype
(E
)));
703 -- A nondiscriminant selected component where the component
704 -- is an anonymous access type means that its associated
705 -- level is that of the containing type - see RM 3.10.2 (16).
707 -- Note that when restriction No_Dynamic_Accessibility_Checks is
708 -- in effect we treat discriminant components as regular
712 (Nkind
(E
) = N_Selected_Component
713 and then Ekind
(Etype
(E
)) = E_Anonymous_Access_Type
714 and then Ekind
(Etype
(Pre
)) /= E_Anonymous_Access_Type
715 and then (not (Nkind
(Selector_Name
(E
)) in N_Has_Entity
716 and then Ekind
(Entity
(Selector_Name
(E
)))
719 -- The alternative accessibility models both treat
720 -- discriminants as regular components.
722 or else (No_Dynamic_Accessibility_Checks_Enabled
(E
)
723 and then Allow_Alt_Model
)))
725 -- Arrays featuring components of anonymous access components
726 -- get their corresponding level from their containing type's
730 (Nkind
(E
) = N_Indexed_Component
731 and then Ekind
(Etype
(E
)) = E_Anonymous_Access_Type
732 and then Ekind
(Etype
(Pre
)) in Array_Kind
733 and then Ekind
(Component_Type
(Base_Type
(Etype
(Pre
))))
734 = E_Anonymous_Access_Type
)
736 -- When restriction No_Dynamic_Accessibility_Checks is active
737 -- and -gnatd_b set, the level is that of the designated type.
740 and then No_Dynamic_Accessibility_Checks_Enabled
(E
)
741 and then Debug_Flag_Underscore_B
743 return Make_Level_Literal
744 (Typ_Access_Level
(Etype
(E
)));
747 -- Otherwise proceed normally
749 return Make_Level_Literal
750 (Typ_Access_Level
(Etype
(Prefix
(E
))));
752 -- The accessibility calculation routine that handles function
753 -- calls (Function_Call_Level) assumes, in the case the
754 -- result is of an anonymous access type, that the result will be
755 -- used "in its entirety" when the call is present within an
756 -- assignment or object declaration.
758 -- To properly handle cases where the result is not used in its
759 -- entirety, we test if the prefix of the component in question is
760 -- a function call, which tells us that one of its components has
761 -- been identified and is being accessed. Therefore we can
762 -- conclude that the result is not used "in its entirety"
763 -- according to RM 3.10.2 (10.2/3).
765 elsif Nkind
(Pre
) = N_Function_Call
766 and then not Is_Named_Access_Type
(Etype
(Pre
))
768 -- Dynamic checks are generated when we are within a return
769 -- value or we are in a function call within an anonymous
770 -- access discriminant constraint of a return object (signified
771 -- by In_Return_Context) on the side of the callee.
773 -- So, in this case, return a library accessibility level to
774 -- null out the check on the side of the caller.
776 if (In_Return_Value
(E
)
777 or else In_Return_Context
)
778 and then Level
/= Dynamic_Level
780 return Make_Level_Literal
781 (Scope_Depth
(Standard_Standard
));
784 return Make_Level_Literal
785 (Innermost_Master_Scope_Depth
(Expr
));
787 -- Otherwise, continue recursing over the expression prefixes
790 return Accessibility_Level
(Prefix
(E
));
793 -- Qualified expressions
795 when N_Qualified_Expression
=>
796 if Is_Named_Access_Type
(Etype
(E
)) then
797 return Make_Level_Literal
798 (Typ_Access_Level
(Etype
(E
)));
800 return Accessibility_Level
(Expression
(E
));
803 -- Handle function calls
805 when N_Function_Call
=>
806 return Function_Call_Or_Allocator_Level
(E
);
808 -- Explicit dereference accessibility level calculation
810 when N_Explicit_Dereference
=>
811 Pre
:= Original_Node
(Prefix
(E
));
813 -- The prefix is a named access type so the level is taken from
816 if Is_Named_Access_Type
(Etype
(Pre
)) then
817 return Make_Level_Literal
(Typ_Access_Level
(Etype
(Pre
)));
819 -- Otherwise, recurse deeper
822 return Accessibility_Level
(Prefix
(E
));
827 when N_Type_Conversion | N_Unchecked_Type_Conversion
=>
828 -- View conversions are special in that they require use to
829 -- inspect the expression of the type conversion.
831 -- Allocators of anonymous access types are internally generated,
832 -- so recurse deeper in that case as well.
834 if Is_View_Conversion
(E
)
835 or else Ekind
(Etype
(E
)) = E_Anonymous_Access_Type
837 return Accessibility_Level
(Expression
(E
));
839 -- We don't care about the master if we are looking at a named
842 elsif Is_Named_Access_Type
(Etype
(E
)) then
843 return Make_Level_Literal
844 (Typ_Access_Level
(Etype
(E
)));
846 -- In section RM 3.10.2 (10/4) the accessibility rules for
847 -- aggregates and value conversions are outlined. Are these
848 -- followed in the case of initialization of an object ???
850 -- Should use Innermost_Master_Scope_Depth ???
853 return Accessibility_Level
(Current_Scope
);
856 -- Default to the type accessibility level for the type of the
857 -- expression's entity.
860 return Make_Level_Literal
(Typ_Access_Level
(Etype
(E
)));
862 end Accessibility_Level
;
864 -------------------------------
865 -- Apply_Accessibility_Check --
866 -------------------------------
868 procedure Apply_Accessibility_Check
871 Insert_Node
: Node_Id
)
873 Loc
: constant Source_Ptr
:= Sloc
(N
);
875 Check_Cond
: Node_Id
;
876 Param_Ent
: Entity_Id
:= Param_Entity
(N
);
877 Param_Level
: Node_Id
;
878 Type_Level
: Node_Id
;
881 -- Verify we haven't tried to add a dynamic accessibility check when we
884 pragma Assert
(not No_Dynamic_Accessibility_Checks_Enabled
(N
));
886 if Ada_Version
>= Ada_2012
887 and then No
(Param_Ent
)
888 and then Is_Entity_Name
(N
)
889 and then Ekind
(Entity
(N
)) in E_Constant | E_Variable
890 and then Present
(Effective_Extra_Accessibility
(Entity
(N
)))
892 Param_Ent
:= Entity
(N
);
893 while Present
(Renamed_Object
(Param_Ent
)) loop
894 -- Renamed_Object must return an Entity_Name here
895 -- because of preceding "Present (E_E_A (...))" test.
897 Param_Ent
:= Entity
(Renamed_Object
(Param_Ent
));
901 if Inside_A_Generic
then
904 -- Only apply the run-time check if the access parameter has an
905 -- associated extra access level parameter and when accessibility checks
908 elsif Present
(Param_Ent
)
909 and then Present
(Get_Dynamic_Accessibility
(Param_Ent
))
910 and then not Accessibility_Checks_Suppressed
(Param_Ent
)
911 and then not Accessibility_Checks_Suppressed
(Typ
)
913 -- Obtain the parameter's accessibility level
916 New_Occurrence_Of
(Get_Dynamic_Accessibility
(Param_Ent
), Loc
);
918 -- Use the dynamic accessibility parameter for the function's result
919 -- when one has been created instead of statically referring to the
920 -- deepest type level so as to appropriatly handle the rules for
921 -- RM 3.10.2 (10.1/3).
923 if Ekind
(Scope
(Param_Ent
)) = E_Function
924 and then In_Return_Value
(N
)
925 and then Ekind
(Typ
) = E_Anonymous_Access_Type
927 -- Associate the level of the result type to the extra result
928 -- accessibility parameter belonging to the current function.
930 if Present
(Extra_Accessibility_Of_Result
(Scope
(Param_Ent
))) then
933 (Extra_Accessibility_Of_Result
(Scope
(Param_Ent
)), Loc
);
935 -- In Ada 2005 and earlier modes, a result extra accessibility
936 -- parameter is not generated and no dynamic check is performed.
942 -- Otherwise get the type's accessibility level normally
946 Make_Integer_Literal
(Loc
, Deepest_Type_Access_Level
(Typ
));
949 -- Raise Program_Error if the accessibility level of the access
950 -- parameter is deeper than the level of the target access type.
954 Left_Opnd
=> Param_Level
,
955 Right_Opnd
=> Type_Level
);
957 Insert_Action
(Insert_Node
,
958 Make_Raise_Program_Error
(Loc
,
959 Condition
=> Check_Cond
,
960 Reason
=> PE_Accessibility_Check_Failed
));
962 Analyze_And_Resolve
(N
);
964 -- If constant folding has happened on the condition for the
965 -- generated error, then warn about it being unconditional.
967 if Nkind
(Check_Cond
) = N_Identifier
968 and then Entity
(Check_Cond
) = Standard_True
970 Error_Msg_Warn
:= SPARK_Mode
/= On
;
971 Error_Msg_N
("accessibility check fails<<", N
);
972 Error_Msg_N
("\Program_Error [<<", N
);
975 end Apply_Accessibility_Check
;
977 ---------------------------------------------
978 -- Apply_Accessibility_Check_For_Allocator --
979 ---------------------------------------------
981 procedure Apply_Accessibility_Check_For_Allocator
985 Built_In_Place
: Boolean := False)
987 Loc
: constant Source_Ptr
:= Sloc
(N
);
988 PtrT
: constant Entity_Id
:= Etype
(N
);
989 DesigT
: constant Entity_Id
:= Designated_Type
(PtrT
);
990 Pool_Id
: constant Entity_Id
:= Associated_Storage_Pool
(PtrT
);
998 if Ada_Version
>= Ada_2005
999 and then Is_Class_Wide_Type
(DesigT
)
1000 and then Tagged_Type_Expansion
1001 and then not Scope_Suppress
.Suppress
(Accessibility_Check
)
1002 and then not No_Dynamic_Accessibility_Checks_Enabled
(Ref
)
1004 (Type_Access_Level
(Etype
(Exp
)) > Type_Access_Level
(PtrT
)
1006 (Is_Class_Wide_Type
(Etype
(Exp
))
1007 and then Scope
(PtrT
) /= Current_Scope
))
1009 -- If the allocator was built in place, Ref is already a reference
1010 -- to the access object initialized to the result of the allocator
1011 -- (see Exp_Ch6.Make_Build_In_Place_Call_In_Allocator). We call
1012 -- Remove_Side_Effects for cases where the build-in-place call may
1013 -- still be the prefix of the reference (to avoid generating
1014 -- duplicate calls). Otherwise, it is the entity associated with
1015 -- the object containing the address of the allocated object.
1017 if Built_In_Place
then
1018 Remove_Side_Effects
(Ref
);
1019 Obj_Ref
:= New_Copy_Tree
(Ref
);
1021 Obj_Ref
:= New_Occurrence_Of
(Ref
, Loc
);
1024 -- For access to interface types we must generate code to displace
1025 -- the pointer to the base of the object since the subsequent code
1026 -- references components located in the TSD of the object (which
1027 -- is associated with the primary dispatch table --see a-tags.ads)
1028 -- and also generates code invoking Free, which requires also a
1029 -- reference to the base of the unallocated object.
1031 if Is_Interface
(DesigT
) and then Tagged_Type_Expansion
then
1033 Unchecked_Convert_To
(Etype
(Obj_Ref
),
1034 Make_Function_Call
(Loc
,
1036 New_Occurrence_Of
(RTE
(RE_Base_Address
), Loc
),
1037 Parameter_Associations
=> New_List
(
1038 Unchecked_Convert_To
(RTE
(RE_Address
),
1039 New_Copy_Tree
(Obj_Ref
)))));
1042 -- Step 1: Create the object clean up code
1046 -- Deallocate the object if the accessibility check fails. This is
1047 -- done only on targets or profiles that support deallocation.
1051 if RTE_Available
(RE_Free
) then
1052 Free_Stmt
:= Make_Free_Statement
(Loc
, New_Copy_Tree
(Obj_Ref
));
1053 Set_Storage_Pool
(Free_Stmt
, Pool_Id
);
1055 Append_To
(Stmts
, Free_Stmt
);
1057 -- The target or profile cannot deallocate objects
1063 -- Finalize the object if applicable. Generate:
1065 -- [Deep_]Finalize (Obj_Ref.all);
1067 if Needs_Finalization
(DesigT
)
1068 and then not No_Heap_Finalization
(PtrT
)
1073 Make_Explicit_Dereference
(Loc
, New_Copy
(Obj_Ref
)),
1076 -- Guard against a missing [Deep_]Finalize when the designated
1077 -- type was not properly frozen.
1079 if No
(Fin_Call
) then
1080 Fin_Call
:= Make_Null_Statement
(Loc
);
1083 -- When the target or profile supports deallocation, wrap the
1084 -- finalization call in a block to ensure proper deallocation even
1085 -- if finalization fails. Generate:
1095 if Present
(Free_Stmt
) then
1097 Make_Block_Statement
(Loc
,
1098 Handled_Statement_Sequence
=>
1099 Make_Handled_Sequence_Of_Statements
(Loc
,
1100 Statements
=> New_List
(Fin_Call
),
1102 Exception_Handlers
=> New_List
(
1103 Make_Exception_Handler
(Loc
,
1104 Exception_Choices
=> New_List
(
1105 Make_Others_Choice
(Loc
)),
1106 Statements
=> New_List
(
1107 New_Copy_Tree
(Free_Stmt
),
1108 Make_Raise_Statement
(Loc
))))));
1111 Prepend_To
(Stmts
, Fin_Call
);
1114 -- Signal the accessibility failure through a Program_Error
1117 Make_Raise_Program_Error
(Loc
,
1118 Reason
=> PE_Accessibility_Check_Failed
));
1120 -- Step 2: Create the accessibility comparison
1126 Make_Attribute_Reference
(Loc
,
1128 Attribute_Name
=> Name_Tag
);
1130 -- For tagged types, determine the accessibility level by looking at
1131 -- the type specific data of the dispatch table. Generate:
1133 -- Type_Specific_Data (Address (Ref'Tag)).Access_Level
1135 if Tagged_Type_Expansion
then
1136 Cond
:= Build_Get_Access_Level
(Loc
, Obj_Ref
);
1138 -- Use a runtime call to determine the accessibility level when
1139 -- compiling on virtual machine targets. Generate:
1141 -- Get_Access_Level (Ref'Tag)
1145 Make_Function_Call
(Loc
,
1147 New_Occurrence_Of
(RTE
(RE_Get_Access_Level
), Loc
),
1148 Parameter_Associations
=> New_List
(Obj_Ref
));
1154 Right_Opnd
=> Accessibility_Level
(N
, Dynamic_Level
));
1156 -- Due to the complexity and side effects of the check, utilize an if
1157 -- statement instead of the regular Program_Error circuitry.
1160 Make_Implicit_If_Statement
(N
,
1162 Then_Statements
=> Stmts
));
1164 end Apply_Accessibility_Check_For_Allocator
;
1166 ------------------------------------------
1167 -- Check_Return_Construct_Accessibility --
1168 ------------------------------------------
1170 procedure Check_Return_Construct_Accessibility
1171 (Return_Stmt
: Node_Id
;
1172 Stm_Entity
: Entity_Id
)
1174 Loc
: constant Source_Ptr
:= Sloc
(Return_Stmt
);
1175 Scope_Id
: constant Entity_Id
:= Return_Applies_To
(Stm_Entity
);
1177 R_Type
: constant Entity_Id
:= Etype
(Scope_Id
);
1178 -- Function result subtype
1180 function First_Selector
(Assoc
: Node_Id
) return Node_Id
;
1181 -- Obtain the first selector or choice from a given association
1183 function Is_Formal_Of_Current_Function
1184 (Assoc_Expr
: Node_Id
) return Boolean;
1185 -- Predicate to test if a given expression associated with a
1186 -- discriminant is a formal parameter to the function in which the
1187 -- return construct we checking applies to.
1189 --------------------
1190 -- First_Selector --
1191 --------------------
1193 function First_Selector
(Assoc
: Node_Id
) return Node_Id
is
1195 if Nkind
(Assoc
) = N_Component_Association
then
1196 return First
(Choices
(Assoc
));
1198 elsif Nkind
(Assoc
) = N_Discriminant_Association
then
1199 return (First
(Selector_Names
(Assoc
)));
1202 raise Program_Error
;
1206 -----------------------------------
1207 -- Is_Formal_Of_Current_Function --
1208 -----------------------------------
1210 function Is_Formal_Of_Current_Function
1211 (Assoc_Expr
: Node_Id
) return Boolean is
1213 return Is_Entity_Name
(Assoc_Expr
)
1214 and then Enclosing_Subprogram
1215 (Entity
(Assoc_Expr
)) = Scope_Id
1216 and then Is_Formal
(Entity
(Assoc_Expr
));
1217 end Is_Formal_Of_Current_Function
;
1219 -- Local declarations
1221 Assoc
: Node_Id
:= Empty
;
1222 -- Assoc should perhaps be renamed and declared as a
1223 -- Node_Or_Entity_Id since it encompasses not only component and
1224 -- discriminant associations, but also discriminant components within
1225 -- a type declaration or subtype indication ???
1227 Assoc_Expr
: Node_Id
;
1228 Assoc_Present
: Boolean := False;
1230 Check_Cond
: Node_Id
;
1231 Unseen_Disc_Count
: Nat
:= 0;
1232 Seen_Discs
: Elist_Id
;
1234 First_Disc
: Entity_Id
;
1237 Return_Con
: Node_Id
;
1240 -- Start of processing for Check_Return_Construct_Accessibility
1243 -- Only perform checks on record types with access discriminants and
1244 -- non-internally generated functions.
1246 if not Is_Record_Type
(R_Type
)
1247 or else not Has_Anonymous_Access_Discriminant
(R_Type
)
1248 or else not Comes_From_Source
(Return_Stmt
)
1253 -- We are only interested in return statements
1255 if Nkind
(Return_Stmt
) not in
1256 N_Extended_Return_Statement | N_Simple_Return_Statement
1261 -- Fetch the object from the return statement, in the case of a
1262 -- simple return statement the expression is part of the node.
1264 if Nkind
(Return_Stmt
) = N_Extended_Return_Statement
then
1265 -- Obtain the object definition from the expanded extended return
1267 Return_Con
:= First
(Return_Object_Declarations
(Return_Stmt
));
1268 while Present
(Return_Con
) loop
1269 -- Inspect the original node to avoid object declarations
1270 -- expanded into renamings.
1272 if Nkind
(Original_Node
(Return_Con
)) = N_Object_Declaration
1273 and then Comes_From_Source
(Original_Node
(Return_Con
))
1278 Nlists
.Next
(Return_Con
);
1281 pragma Assert
(Present
(Return_Con
));
1283 -- Could be dealing with a renaming
1285 Return_Con
:= Original_Node
(Return_Con
);
1287 Return_Con
:= Expression
(Return_Stmt
);
1290 -- Obtain the accessibility levels of the expressions associated
1291 -- with all anonymous access discriminants, then generate a
1292 -- dynamic check or static error when relevant.
1294 -- Note the repeated use of Original_Node to avoid checking
1297 Unqual
:= Original_Node
(Unqualify
(Original_Node
(Return_Con
)));
1299 -- Get the corresponding declaration based on the return object's
1302 if Nkind
(Unqual
) = N_Identifier
1303 and then Nkind
(Parent
(Entity
(Unqual
)))
1304 in N_Object_Declaration
1305 | N_Object_Renaming_Declaration
1307 Obj_Decl
:= Original_Node
(Parent
(Entity
(Unqual
)));
1309 -- We were passed the object declaration directly, so use it
1311 elsif Nkind
(Unqual
) in N_Object_Declaration
1312 | N_Object_Renaming_Declaration
1316 -- Otherwise, we are looking at something else
1323 -- Hop up object renamings when present
1325 if Present
(Obj_Decl
)
1326 and then Nkind
(Obj_Decl
) = N_Object_Renaming_Declaration
1328 while Nkind
(Obj_Decl
) = N_Object_Renaming_Declaration
loop
1330 if Nkind
(Name
(Obj_Decl
)) not in N_Entity
then
1331 -- We may be looking at the expansion of iterators or
1332 -- some other internally generated construct, so it is safe
1333 -- to ignore checks ???
1335 if not Comes_From_Source
(Obj_Decl
) then
1339 Obj_Decl
:= Original_Node
1341 (Ultimate_Prefix
(Name
(Obj_Decl
))));
1343 -- Move up to the next declaration based on the object's name
1346 Obj_Decl
:= Original_Node
1347 (Declaration_Node
(Name
(Obj_Decl
)));
1352 -- Obtain the discriminant values from the return aggregate
1354 -- Do we cover extension aggregates correctly ???
1356 if Nkind
(Unqual
) = N_Aggregate
then
1357 if Present
(Expressions
(Unqual
)) then
1358 Assoc
:= First
(Expressions
(Unqual
));
1360 Assoc
:= First
(Component_Associations
(Unqual
));
1363 -- There is an object declaration for the return object
1365 elsif Present
(Obj_Decl
) then
1366 -- When a subtype indication is present in an object declaration
1367 -- it must contain the object's discriminants.
1369 if Nkind
(Object_Definition
(Obj_Decl
)) = N_Subtype_Indication
then
1373 (Object_Definition
(Obj_Decl
))));
1375 -- The object declaration contains an aggregate
1377 elsif Present
(Expression
(Obj_Decl
)) then
1379 if Nkind
(Unqualify
(Expression
(Obj_Decl
))) = N_Aggregate
then
1380 -- Grab the first associated discriminant expresion
1383 (Expressions
(Unqualify
(Expression
(Obj_Decl
))))
1387 (Unqualify
(Expression
(Obj_Decl
))));
1390 (Component_Associations
1391 (Unqualify
(Expression
(Obj_Decl
))));
1394 -- Otherwise, this is something else
1400 -- There are no supplied discriminants in the object declaration,
1401 -- so get them from the type definition since they must be default
1404 -- Do we handle constrained subtypes correctly ???
1406 elsif Nkind
(Unqual
) = N_Object_Declaration
then
1407 Assoc
:= First_Discriminant
1408 (Etype
(Object_Definition
(Obj_Decl
)));
1411 Assoc
:= First_Discriminant
(Etype
(Unqual
));
1414 -- When we are not looking at an aggregate or an identifier, return
1415 -- since any other construct (like a function call) is not
1416 -- applicable since checks will be performed on the side of the
1423 -- Obtain the discriminants so we know the actual type in case the
1424 -- value of their associated expression gets implicitly converted.
1426 if No
(Obj_Decl
) then
1427 pragma Assert
(Nkind
(Unqual
) = N_Aggregate
);
1429 Disc
:= First_Discriminant
(Etype
(Unqual
));
1432 Disc
:= First_Discriminant
1433 (Etype
(Defining_Identifier
(Obj_Decl
)));
1436 -- Preserve the first discriminant for checking named associations
1440 -- Count the number of discriminants for processing an aggregate
1441 -- which includes an others.
1444 while Present
(Disc
) loop
1445 Unseen_Disc_Count
:= Unseen_Disc_Count
+ 1;
1447 Next_Discriminant
(Disc
);
1450 Seen_Discs
:= New_Elmt_List
;
1452 -- Loop through each of the discriminants and check each expression
1453 -- associated with an anonymous access discriminant.
1455 -- When named associations occur in the return aggregate then
1456 -- discriminants can be in any order, so we need to ensure we do
1457 -- not continue to loop when all discriminants have been seen.
1460 while Present
(Assoc
)
1461 and then (Present
(Disc
) or else Assoc_Present
)
1462 and then Unseen_Disc_Count
> 0
1464 -- Handle named associations by searching through the names of
1465 -- the relevant discriminant components.
1468 in N_Component_Association | N_Discriminant_Association
1470 Assoc_Expr
:= Expression
(Assoc
);
1471 Assoc_Present
:= True;
1473 -- We currently don't handle box initialized discriminants,
1474 -- however, since default initialized anonymous access
1475 -- discriminants are a corner case, this is ok for now ???
1477 if Nkind
(Assoc
) = N_Component_Association
1478 and then Box_Present
(Assoc
)
1480 if Nkind
(First_Selector
(Assoc
)) = N_Others_Choice
then
1481 Unseen_Disc_Count
:= 0;
1484 -- When others is present we must identify a discriminant we
1485 -- haven't already seen so as to get the appropriate type for
1486 -- the static accessibility check.
1488 -- This works because all components within an others clause
1489 -- must have the same type.
1491 elsif Nkind
(First_Selector
(Assoc
)) = N_Others_Choice
then
1494 Outer
: while Present
(Disc
) loop
1496 Current_Seen_Disc
: Elmt_Id
;
1498 -- Move through the list of identified discriminants
1500 Current_Seen_Disc
:= First_Elmt
(Seen_Discs
);
1501 while Present
(Current_Seen_Disc
) loop
1502 -- Exit the loop when we found a match
1505 Chars
(Node
(Current_Seen_Disc
)) = Chars
(Disc
);
1507 Next_Elmt
(Current_Seen_Disc
);
1510 -- When we have exited the above loop without finding
1511 -- a match then we know that Disc has not been seen.
1513 exit Outer
when No
(Current_Seen_Disc
);
1516 Next_Discriminant
(Disc
);
1519 -- If we got to an others clause with a non-zero
1520 -- discriminant count there must be a discriminant left to
1523 pragma Assert
(Present
(Disc
));
1525 -- Set the unseen discriminant count to zero because we know
1526 -- an others clause sets all remaining components of an
1529 Unseen_Disc_Count
:= 0;
1531 -- Move through each of the selectors in the named association
1532 -- and obtain a discriminant for accessibility checking if one
1533 -- is referenced in the list. Also track which discriminants
1534 -- are referenced for the purpose of handling an others clause.
1538 Assoc_Choice
: Node_Id
;
1539 Curr_Disc
: Node_Id
;
1543 Curr_Disc
:= First_Disc
;
1544 while Present
(Curr_Disc
) loop
1545 -- Check each of the choices in the associations for a
1546 -- match to the name of the current discriminant.
1548 Assoc_Choice
:= First_Selector
(Assoc
);
1549 while Present
(Assoc_Choice
) loop
1550 -- When the name matches we track that we have seen
1551 -- the discriminant, but instead of exiting the
1552 -- loop we continue iterating to make sure all the
1553 -- discriminants within the named association get
1556 if Chars
(Assoc_Choice
) = Chars
(Curr_Disc
) then
1557 Append_Elmt
(Curr_Disc
, Seen_Discs
);
1560 Unseen_Disc_Count
:= Unseen_Disc_Count
- 1;
1563 Next
(Assoc_Choice
);
1566 Next_Discriminant
(Curr_Disc
);
1571 -- Unwrap the associated expression if we are looking at a default
1572 -- initialized type declaration. In this case Assoc is not really
1573 -- an association, but a component declaration. Should Assoc be
1574 -- renamed in some way to be more clear ???
1576 -- This occurs when the return object does not initialize
1577 -- discriminant and instead relies on the type declaration for
1578 -- their supplied values.
1580 elsif Nkind
(Assoc
) in N_Entity
1581 and then Ekind
(Assoc
) = E_Discriminant
1583 Append_Elmt
(Disc
, Seen_Discs
);
1585 Assoc_Expr
:= Discriminant_Default_Value
(Assoc
);
1586 Unseen_Disc_Count
:= Unseen_Disc_Count
- 1;
1588 -- Otherwise, there is nothing to do because Assoc is an
1589 -- expression within the return aggregate itself.
1592 Append_Elmt
(Disc
, Seen_Discs
);
1594 Assoc_Expr
:= Assoc
;
1595 Unseen_Disc_Count
:= Unseen_Disc_Count
- 1;
1598 -- Check the accessibility level of the expression when the
1599 -- discriminant is of an anonymous access type.
1601 if Present
(Assoc_Expr
)
1602 and then Present
(Disc
)
1603 and then Ekind
(Etype
(Disc
)) = E_Anonymous_Access_Type
1605 -- We disable the check when we have a tagged return type and
1606 -- the associated expression for the discriminant is a formal
1607 -- parameter since the check would require us to compare the
1608 -- accessibility level of Assoc_Expr to the level of the
1609 -- Extra_Accessibility_Of_Result of the function - which is
1610 -- currently disabled for functions with tagged return types.
1611 -- This may change in the future ???
1613 -- See Needs_Result_Accessibility_Level for details.
1616 (No
(Extra_Accessibility_Of_Result
(Scope_Id
))
1617 and then Is_Formal_Of_Current_Function
(Assoc_Expr
)
1618 and then Is_Tagged_Type
(Etype
(Scope_Id
)))
1620 -- Generate a dynamic check based on the extra accessibility of
1621 -- the result or the scope of the current function.
1625 Left_Opnd
=> Accessibility_Level
1626 (Expr
=> Assoc_Expr
,
1627 Level
=> Dynamic_Level
,
1628 In_Return_Context
=> True),
1630 (if Present
(Extra_Accessibility_Of_Result
(Scope_Id
))
1632 -- When Assoc_Expr is a formal we have to look at the
1633 -- extra accessibility-level formal associated with
1636 and then Is_Formal_Of_Current_Function
(Assoc_Expr
)
1639 (Extra_Accessibility_Of_Result
(Scope_Id
), Loc
)
1641 -- Otherwise, we compare the level of Assoc_Expr to the
1642 -- scope of the current function.
1645 Make_Integer_Literal
1646 (Loc
, Scope_Depth
(Scope
(Scope_Id
)))));
1648 Insert_Before_And_Analyze
(Return_Stmt
,
1649 Make_Raise_Program_Error
(Loc
,
1650 Condition
=> Check_Cond
,
1651 Reason
=> PE_Accessibility_Check_Failed
));
1653 -- If constant folding has happened on the condition for the
1654 -- generated error, then warn about it being unconditional when
1655 -- we know an error will be raised.
1657 if Nkind
(Check_Cond
) = N_Identifier
1658 and then Entity
(Check_Cond
) = Standard_True
1661 ("access discriminant in return object would be a dangling"
1662 & " reference", Return_Stmt
);
1666 -- Iterate over the discriminants, except when we have encountered
1667 -- a named association since the discriminant order becomes
1668 -- irrelevant in that case.
1670 if not Assoc_Present
then
1671 Next_Discriminant
(Disc
);
1674 -- Iterate over associations
1676 if not Is_List_Member
(Assoc
) then
1679 Nlists
.Next
(Assoc
);
1682 end Check_Return_Construct_Accessibility
;
1684 -------------------------------
1685 -- Deepest_Type_Access_Level --
1686 -------------------------------
1688 function Deepest_Type_Access_Level
1690 Allow_Alt_Model
: Boolean := True) return Uint
1693 if Ekind
(Typ
) = E_Anonymous_Access_Type
1694 and then not Is_Local_Anonymous_Access
(Typ
)
1695 and then Nkind
(Associated_Node_For_Itype
(Typ
)) = N_Object_Declaration
1697 -- No_Dynamic_Accessibility_Checks override for alternative
1698 -- accessibility model.
1701 and then No_Dynamic_Accessibility_Checks_Enabled
(Typ
)
1703 return Type_Access_Level
(Typ
, Allow_Alt_Model
);
1706 -- Typ is the type of an Ada 2012 stand-alone object of an anonymous
1710 Scope_Depth
(Enclosing_Dynamic_Scope
1711 (Defining_Identifier
1712 (Associated_Node_For_Itype
(Typ
))));
1714 -- For generic formal type, return Int'Last (infinite).
1715 -- See comment preceding Is_Generic_Type call in Type_Access_Level.
1717 elsif Is_Generic_Type
(Root_Type
(Typ
)) then
1718 return UI_From_Int
(Int
'Last);
1721 return Type_Access_Level
(Typ
, Allow_Alt_Model
);
1723 end Deepest_Type_Access_Level
;
1725 -----------------------------------
1726 -- Effective_Extra_Accessibility --
1727 -----------------------------------
1729 function Effective_Extra_Accessibility
(Id
: Entity_Id
) return Entity_Id
is
1731 if Present
(Renamed_Object
(Id
))
1732 and then Is_Entity_Name
(Renamed_Object
(Id
))
1734 return Effective_Extra_Accessibility
(Entity
(Renamed_Object
(Id
)));
1736 return Extra_Accessibility
(Id
);
1738 end Effective_Extra_Accessibility
;
1740 -------------------------------
1741 -- Get_Dynamic_Accessibility --
1742 -------------------------------
1744 function Get_Dynamic_Accessibility
(E
: Entity_Id
) return Entity_Id
is
1746 -- When minimum accessibility is set for E then we utilize it - except
1747 -- in a few edge cases like the expansion of select statements where
1748 -- generated subprogram may attempt to unnecessarily use a minimum
1749 -- accessibility object declared outside of scope.
1751 -- To avoid these situations where expansion may get complex we verify
1752 -- that the minimum accessibility object is within scope.
1755 and then Present
(Minimum_Accessibility
(E
))
1756 and then In_Open_Scopes
(Scope
(Minimum_Accessibility
(E
)))
1758 return Minimum_Accessibility
(E
);
1761 return Extra_Accessibility
(E
);
1762 end Get_Dynamic_Accessibility
;
1764 -----------------------
1765 -- Has_Access_Values --
1766 -----------------------
1768 function Has_Access_Values
(T
: Entity_Id
) return Boolean
1770 Typ
: constant Entity_Id
:= Underlying_Type
(T
);
1773 -- Case of a private type which is not completed yet. This can only
1774 -- happen in the case of a generic formal type appearing directly, or
1775 -- as a component of the type to which this function is being applied
1776 -- at the top level. Return False in this case, since we certainly do
1777 -- not know that the type contains access types.
1782 elsif Is_Access_Type
(Typ
) then
1785 elsif Is_Array_Type
(Typ
) then
1786 return Has_Access_Values
(Component_Type
(Typ
));
1788 elsif Is_Record_Type
(Typ
) then
1793 -- Loop to check components
1795 Comp
:= First_Component_Or_Discriminant
(Typ
);
1796 while Present
(Comp
) loop
1798 -- Check for access component, tag field does not count, even
1799 -- though it is implemented internally using an access type.
1801 if Has_Access_Values
(Etype
(Comp
))
1802 and then Chars
(Comp
) /= Name_uTag
1807 Next_Component_Or_Discriminant
(Comp
);
1816 end Has_Access_Values
;
1818 ---------------------------------------
1819 -- Has_Anonymous_Access_Discriminant --
1820 ---------------------------------------
1822 function Has_Anonymous_Access_Discriminant
(Typ
: Entity_Id
) return Boolean
1827 if not Has_Discriminants
(Typ
) then
1831 Disc
:= First_Discriminant
(Typ
);
1832 while Present
(Disc
) loop
1833 if Ekind
(Etype
(Disc
)) = E_Anonymous_Access_Type
then
1837 Next_Discriminant
(Disc
);
1841 end Has_Anonymous_Access_Discriminant
;
1843 --------------------------------------------
1844 -- Has_Unconstrained_Access_Discriminants --
1845 --------------------------------------------
1847 function Has_Unconstrained_Access_Discriminants
1848 (Subtyp
: Entity_Id
) return Boolean
1853 if Has_Discriminants
(Subtyp
)
1854 and then not Is_Constrained
(Subtyp
)
1856 Discr
:= First_Discriminant
(Subtyp
);
1857 while Present
(Discr
) loop
1858 if Ekind
(Etype
(Discr
)) = E_Anonymous_Access_Type
then
1862 Next_Discriminant
(Discr
);
1867 end Has_Unconstrained_Access_Discriminants
;
1869 --------------------------------
1870 -- Is_Anonymous_Access_Actual --
1871 --------------------------------
1873 function Is_Anonymous_Access_Actual
(N
: Node_Id
) return Boolean is
1876 if Ekind
(Etype
(N
)) /= E_Anonymous_Access_Type
then
1882 and then Nkind
(Par
) in N_Case_Expression
1884 | N_Parameter_Association
1886 Par
:= Parent
(Par
);
1888 return Nkind
(Par
) in N_Subprogram_Call
;
1889 end Is_Anonymous_Access_Actual
;
1891 --------------------------------------
1892 -- Is_Special_Aliased_Formal_Access --
1893 --------------------------------------
1895 function Is_Special_Aliased_Formal_Access
1897 In_Return_Context
: Boolean := False) return Boolean
1899 Scop
: constant Entity_Id
:= Current_Subprogram
;
1901 -- Verify the expression is an access reference to 'Access within a
1902 -- return statement as this is the only time an explicitly aliased
1903 -- formal has different semantics.
1905 if Nkind
(Exp
) /= N_Attribute_Reference
1906 or else Get_Attribute_Id
(Attribute_Name
(Exp
)) /= Attribute_Access
1907 or else not (In_Return_Value
(Exp
)
1908 or else In_Return_Context
)
1909 or else not Needs_Result_Accessibility_Level
(Scop
)
1914 -- Check if the prefix of the reference is indeed an explicitly aliased
1915 -- formal parameter for the function Scop. Additionally, we must check
1916 -- that Scop returns an anonymous access type, otherwise the special
1917 -- rules dictating a need for a dynamic check are not in effect.
1919 return Is_Entity_Name
(Prefix
(Exp
))
1920 and then Is_Explicitly_Aliased
(Entity
(Prefix
(Exp
)));
1921 end Is_Special_Aliased_Formal_Access
;
1923 --------------------------------------
1924 -- Needs_Result_Accessibility_Level --
1925 --------------------------------------
1927 function Needs_Result_Accessibility_Level
1928 (Func_Id
: Entity_Id
) return Boolean
1930 Func_Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Func_Id
));
1932 function Has_Unconstrained_Access_Discriminant_Component
1933 (Comp_Typ
: Entity_Id
) return Boolean;
1934 -- Returns True if any component of the type has an unconstrained access
1937 -----------------------------------------------------
1938 -- Has_Unconstrained_Access_Discriminant_Component --
1939 -----------------------------------------------------
1941 function Has_Unconstrained_Access_Discriminant_Component
1942 (Comp_Typ
: Entity_Id
) return Boolean
1945 if not Is_Limited_Type
(Comp_Typ
) then
1948 -- Only limited types can have access discriminants with
1951 elsif Has_Unconstrained_Access_Discriminants
(Comp_Typ
) then
1954 elsif Is_Array_Type
(Comp_Typ
) then
1955 return Has_Unconstrained_Access_Discriminant_Component
1956 (Underlying_Type
(Component_Type
(Comp_Typ
)));
1958 elsif Is_Record_Type
(Comp_Typ
) then
1963 Comp
:= First_Component
(Comp_Typ
);
1964 while Present
(Comp
) loop
1965 if Has_Unconstrained_Access_Discriminant_Component
1966 (Underlying_Type
(Etype
(Comp
)))
1971 Next_Component
(Comp
);
1977 end Has_Unconstrained_Access_Discriminant_Component
;
1979 Disable_Tagged_Cases
: constant Boolean := True;
1980 -- Flag used to temporarily disable a "True" result for tagged types.
1981 -- See comments further below for details.
1983 -- Start of processing for Needs_Result_Accessibility_Level
1986 -- False if completion unavailable, which can happen when we are
1987 -- analyzing an abstract subprogram or if the subprogram has
1988 -- delayed freezing.
1990 if No
(Func_Typ
) then
1993 -- False if not a function, also handle enum-lit renames case
1995 elsif Func_Typ
= Standard_Void_Type
1996 or else Is_Scalar_Type
(Func_Typ
)
2000 -- Handle a corner case, a cross-dialect subp renaming. For example,
2001 -- an Ada 2012 renaming of an Ada 2005 subprogram. This can occur when
2002 -- an Ada 2005 (or earlier) unit references predefined run-time units.
2004 elsif Present
(Alias
(Func_Id
)) then
2006 -- Unimplemented: a cross-dialect subp renaming which does not set
2007 -- the Alias attribute (e.g., a rename of a dereference of an access
2008 -- to subprogram value). ???
2010 return Present
(Extra_Accessibility_Of_Result
(Alias
(Func_Id
)));
2012 -- Remaining cases require Ada 2012 mode, unless they are dispatching
2013 -- operations, since they may be overridden by Ada_2012 primitives.
2015 elsif Ada_Version
< Ada_2012
2016 and then not Is_Dispatching_Operation
(Func_Id
)
2020 -- Handle the situation where a result is an anonymous access type
2021 -- RM 3.10.2 (10.3/3).
2023 elsif Ekind
(Func_Typ
) = E_Anonymous_Access_Type
then
2026 -- In the case of, say, a null tagged record result type, the need for
2027 -- this extra parameter might not be obvious so this function returns
2028 -- True for all tagged types for compatibility reasons.
2030 -- A function with, say, a tagged null controlling result type might
2031 -- be overridden by a primitive of an extension having an access
2032 -- discriminant and the overrider and overridden must have compatible
2033 -- calling conventions (including implicitly declared parameters).
2035 -- Similarly, values of one access-to-subprogram type might designate
2036 -- both a primitive subprogram of a given type and a function which is,
2037 -- for example, not a primitive subprogram of any type. Again, this
2038 -- requires calling convention compatibility. It might be possible to
2039 -- solve these issues by introducing wrappers, but that is not the
2040 -- approach that was chosen.
2042 -- Note: Despite the reasoning noted above, the extra accessibility
2043 -- parameter for tagged types is disabled for performance reasons.
2045 elsif Is_Tagged_Type
(Func_Typ
) then
2046 return not Disable_Tagged_Cases
;
2048 elsif Has_Unconstrained_Access_Discriminants
(Func_Typ
) then
2051 elsif Has_Unconstrained_Access_Discriminant_Component
(Func_Typ
) then
2054 -- False for all other cases
2059 end Needs_Result_Accessibility_Level
;
2061 ------------------------------------------
2062 -- Prefix_With_Safe_Accessibility_Level --
2063 ------------------------------------------
2065 function Prefix_With_Safe_Accessibility_Level
2067 Typ
: Entity_Id
) return Boolean
2069 P
: constant Node_Id
:= Prefix
(N
);
2070 Aname
: constant Name_Id
:= Attribute_Name
(N
);
2071 Attr_Id
: constant Attribute_Id
:= Get_Attribute_Id
(Aname
);
2072 Btyp
: constant Entity_Id
:= Base_Type
(Typ
);
2074 function Safe_Value_Conversions
return Boolean;
2075 -- Return False if the prefix has a value conversion of an array type
2077 ----------------------------
2078 -- Safe_Value_Conversions --
2079 ----------------------------
2081 function Safe_Value_Conversions
return Boolean is
2086 if Nkind
(PP
) in N_Selected_Component | N_Indexed_Component
then
2089 elsif Comes_From_Source
(PP
)
2090 and then Nkind
(PP
) in N_Type_Conversion
2091 | N_Unchecked_Type_Conversion
2092 and then Is_Array_Type
(Etype
(PP
))
2096 elsif Comes_From_Source
(PP
)
2097 and then Nkind
(PP
) = N_Qualified_Expression
2098 and then Is_Array_Type
(Etype
(PP
))
2099 and then Nkind
(Original_Node
(Expression
(PP
))) in
2100 N_Aggregate | N_Extension_Aggregate
2110 end Safe_Value_Conversions
;
2112 -- Start of processing for Prefix_With_Safe_Accessibility_Level
2115 -- No check required for unchecked and unrestricted access
2117 if Attr_Id
= Attribute_Unchecked_Access
2118 or else Attr_Id
= Attribute_Unrestricted_Access
2122 -- Check value conversions
2124 elsif Ekind
(Btyp
) = E_General_Access_Type
2125 and then not Safe_Value_Conversions
2131 end Prefix_With_Safe_Accessibility_Level
;
2133 -----------------------------
2134 -- Subprogram_Access_Level --
2135 -----------------------------
2137 function Subprogram_Access_Level
(Subp
: Entity_Id
) return Uint
is
2139 if Present
(Alias
(Subp
)) then
2140 return Subprogram_Access_Level
(Alias
(Subp
));
2142 return Scope_Depth
(Enclosing_Dynamic_Scope
(Subp
));
2144 end Subprogram_Access_Level
;
2146 --------------------------------
2147 -- Static_Accessibility_Level --
2148 --------------------------------
2150 function Static_Accessibility_Level
2152 Level
: Static_Accessibility_Level_Kind
;
2153 In_Return_Context
: Boolean := False) return Uint
2157 (Accessibility_Level
(Expr
, Level
, In_Return_Context
));
2158 end Static_Accessibility_Level
;
2160 -----------------------
2161 -- Type_Access_Level --
2162 -----------------------
2164 function Type_Access_Level
2166 Allow_Alt_Model
: Boolean := True;
2167 Assoc_Ent
: Entity_Id
:= Empty
) return Uint
2169 Btyp
: Entity_Id
:= Base_Type
(Typ
);
2170 Def_Ent
: Entity_Id
;
2173 -- Ada 2005 (AI-230): For most cases of anonymous access types, we
2174 -- simply use the level where the type is declared. This is true for
2175 -- stand-alone object declarations, and for anonymous access types
2176 -- associated with components the level is the same as that of the
2177 -- enclosing composite type. However, special treatment is needed for
2178 -- the cases of access parameters, return objects of an anonymous access
2179 -- type, and, in Ada 95, access discriminants of limited types.
2181 if Is_Access_Type
(Btyp
) then
2182 if Ekind
(Btyp
) = E_Anonymous_Access_Type
then
2183 -- No_Dynamic_Accessibility_Checks restriction override for
2184 -- alternative accessibility model.
2187 and then No_Dynamic_Accessibility_Checks_Enabled
(Btyp
)
2189 -- In the -gnatd_b model, the level of an anonymous access
2190 -- type is always that of the designated type.
2192 if Debug_Flag_Underscore_B
then
2193 return Type_Access_Level
2194 (Designated_Type
(Btyp
), Allow_Alt_Model
);
2197 -- When an anonymous access type's Assoc_Ent is specified,
2198 -- calculate the result based on the general accessibility
2201 -- We would like to use Associated_Node_For_Itype here instead,
2202 -- but in some cases it is not fine grained enough ???
2204 if Present
(Assoc_Ent
) then
2205 return Static_Accessibility_Level
2206 (Assoc_Ent
, Object_Decl_Level
);
2209 -- Otherwise take the context of the anonymous access type into
2212 -- Obtain the defining entity for the internally generated
2213 -- anonymous access type.
2215 Def_Ent
:= Defining_Entity_Or_Empty
2216 (Associated_Node_For_Itype
(Typ
));
2218 if Present
(Def_Ent
) then
2219 -- When the defining entity is a subprogram then we know the
2220 -- anonymous access type Typ has been generated to either
2221 -- describe an anonymous access type formal or an anonymous
2222 -- access result type.
2224 -- Since we are only interested in the formal case, avoid
2225 -- the anonymous access result type.
2227 if Is_Subprogram
(Def_Ent
)
2228 and then not (Ekind
(Def_Ent
) = E_Function
2229 and then Etype
(Def_Ent
) = Typ
)
2231 -- When the type comes from an anonymous access
2232 -- parameter, the level is that of the subprogram
2235 return Scope_Depth
(Def_Ent
);
2237 -- When the type is an access discriminant, the level is
2238 -- that of the type.
2240 elsif Ekind
(Def_Ent
) = E_Discriminant
then
2242 (if Present
(Full_View
(Scope
(Def_Ent
))) then
2243 Full_View
(Scope
(Def_Ent
))
2249 -- If the type is a nonlocal anonymous access type (such as for
2250 -- an access parameter) we treat it as being declared at the
2251 -- library level to ensure that names such as X.all'access don't
2252 -- fail static accessibility checks.
2254 elsif not Is_Local_Anonymous_Access
(Typ
) then
2255 return Scope_Depth
(Standard_Standard
);
2257 -- If this is a return object, the accessibility level is that of
2258 -- the result subtype of the enclosing function. The test here is
2259 -- little complicated, because we have to account for extended
2260 -- return statements that have been rewritten as blocks, in which
2261 -- case we have to find and the Is_Return_Object attribute of the
2262 -- itype's associated object. It would be nice to find a way to
2263 -- simplify this test, but it doesn't seem worthwhile to add a new
2264 -- flag just for purposes of this test. ???
2266 elsif Ekind
(Scope
(Btyp
)) = E_Return_Statement
2269 and then Nkind
(Associated_Node_For_Itype
(Btyp
)) =
2270 N_Object_Declaration
2271 and then Is_Return_Object
2272 (Defining_Identifier
2273 (Associated_Node_For_Itype
(Btyp
))))
2279 Scop
:= Scope
(Scope
(Btyp
));
2280 while Present
(Scop
) loop
2281 exit when Ekind
(Scop
) = E_Function
;
2282 Scop
:= Scope
(Scop
);
2285 -- Treat the return object's type as having the level of the
2286 -- function's result subtype (as per RM05-6.5(5.3/2)).
2288 return Type_Access_Level
(Etype
(Scop
), Allow_Alt_Model
);
2293 Btyp
:= Root_Type
(Btyp
);
2295 -- The accessibility level of anonymous access types associated with
2296 -- discriminants is that of the current instance of the type, and
2297 -- that's deeper than the type itself (AARM 3.10.2 (12.3.21)).
2299 -- AI-402: access discriminants have accessibility based on the
2300 -- object rather than the type in Ada 2005, so the above paragraph
2303 -- ??? Needs completion with rules from AI-416
2305 if Ada_Version
<= Ada_95
2306 and then Ekind
(Typ
) = E_Anonymous_Access_Type
2307 and then Present
(Associated_Node_For_Itype
(Typ
))
2308 and then Nkind
(Associated_Node_For_Itype
(Typ
)) =
2309 N_Discriminant_Specification
2311 return Scope_Depth
(Enclosing_Dynamic_Scope
(Btyp
)) + 1;
2315 -- Return library level for a generic formal type. This is done because
2316 -- RM(10.3.2) says that "The statically deeper relationship does not
2317 -- apply to ... a descendant of a generic formal type". Rather than
2318 -- checking at each point where a static accessibility check is
2319 -- performed to see if we are dealing with a formal type, this rule is
2320 -- implemented by having Type_Access_Level and Deepest_Type_Access_Level
2321 -- return extreme values for a formal type; Deepest_Type_Access_Level
2322 -- returns Int'Last. By calling the appropriate function from among the
2323 -- two, we ensure that the static accessibility check will pass if we
2324 -- happen to run into a formal type. More specifically, we should call
2325 -- Deepest_Type_Access_Level instead of Type_Access_Level whenever the
2326 -- call occurs as part of a static accessibility check and the error
2327 -- case is the case where the type's level is too shallow (as opposed
2330 if Is_Generic_Type
(Root_Type
(Btyp
)) then
2331 return Scope_Depth
(Standard_Standard
);
2334 return Scope_Depth
(Enclosing_Dynamic_Scope
(Btyp
));
2335 end Type_Access_Level
;